1. Field of the Invention
This invention relates in general to the field of resource management, and more particularly to an off-site apparatus and method employing fine-grained weather normalization of energy consumption baseline data for coordinating the use of certain resources in a demand coordination network such that a peak demand of those resources is optimized.
2. Description of the Related Art
The problem with resources such as electrical power, water, fossil fuels, and their derivatives (e.g., natural gas) is that the generation and consumption of a resource both vary with respect to time. Furthermore, the delivery and transport infrastructure is limited in that it cannot instantaneously match generation levels to provide for consumption levels. The delivery and transport infrastructure is limited in supply and the demand for this limited supply is constantly fluctuating. As anyone who has participated in a rolling blackout will concur, the times are more and more frequent when resource consumers are forced to face the realities of limited resource supply.
Most notably, the electrical power generation and distribution community has begun to take proactive measures to protect limited instantaneous supplies of electrical power by imposing a demand charge on consumers in addition to their monthly usage charge. In prior years, consumers merely paid for the total amount of power that they consumed over a billing period. Today, most energy suppliers are not only charging customers for the total amount of electricity they have consumed over the billing period, but they are additionally charging for peak demand. Peak demand is the greatest amount of energy that a customer uses use during a measured period of time, typically on the order of minutes.
For example, consider a factory owner whose building includes 20 air conditioners, each consuming 10 kW when turned on. If they are all on at the same time, then the peak demand for that period is 200 kW. Not only does the energy supplier have to provide for instantaneous generation of this power in conjunction with loads exhibited by its other consumers, but the distribution network that supplies this peak power must be sized such that it delivers 200 kW.
Consequently, high peak demand consumers are required to pay a surcharge to offset the costs of peak energy generation and distribution. And the concept of peak demand charges, while presently being levied only to commercial electricity consumers and to selected residential consumers, is applicable to all residential consumers and consumers of other limited generation and distribution resources as well. Water and natural gas are prime examples of resources that will someday exhibit demand charges.
Yet, consider that in the facility example above it is not time critical or comfort critical to run every air conditioning unit in the building at once. Run times can be staggered, for example, to mitigate peak demand. And this technique is what is presently employed in the industry to lower peak demand. There are very simple ways to stagger run times, and there are very complicated mechanisms that are employed to lower peak demand, but they all utilize variations of what is known in the art as deferral.
Stated simply, deferral means that some devices have to wait to run while other, perhaps higher priority, devices are allowed to run. Another form of deferral is to reduce the duty cycle (i.e., the percentage of the a device cycle that a device is on) of one or more devices in order to share the reduction in peak demand desired. What this means in the air conditioning example above is that some occupants are going to experience discomfort while waiting for their turn to run. When duty cycles are reduced to defer demand, everyone in the facility is going to experience mild discomfort. And as one skilled in the art will appreciate, there is a zone of comfort beyond which productivity falls.
Virtually every system of resource consuming devices exhibits a margin of acceptable operation (“comfort zone” in the air conditioning example above) around which operation of the device in terms of start time, duration, and duty cycle can be deferred. But the present inventors have observed that conventional techniques for controlling peak demand all involve delaying (“deferring”) the start times and durations of devices and/or decreasing the duty cycles, thus in many instances causing local environments to operate outside of their acceptable operational margins. It is either too hot, too cold, not enough water, the motors are not running long enough to get the job done, and etc. Furthermore, these conventional techniques do not take into account the energy lag of a building, that is, the transient response of the building's energy consumption in response to changes in outside temperature.
Accordingly, what is needed is an apparatus and method for managing peak demand of a resource that considers acceptable operational margins in determining when and how long individual devices in a system will run.
What is also needed is a technique for scheduling run times for devices in a controlled system that is capable of advancing the start times and durations of those devices, and that is capable of increasing the duty cycles associated therewith in order to reduce demand while concurrently maintaining operation within acceptable operational margins.
What is additionally needed is a mechanism for modeling and coordinating the operation of a plurality of devices in order to reduce peak demand of a resource, where both advancement and deferral are employed effectively to reduce demand and retain acceptable operational performance.
What is moreover needed is an demand coordination apparatus and method that employs adaptive modeling of local environments and anticipatory scheduling of run times in order to reduce peak demand while maintaining acceptable operation.
Furthermore, what is needed is a demand coordination mechanism perform adaptive modeling of local environments while taking into account the transient energy consumption of a building in response to changes in outside temperature.